The present invention relates to a method of iontophoretically treating acne, furuncles (boils) and similar skin disorders which are characterized by obstructed channels such as hair follicles and sweat ducts in the skin tissue.
Iontophoresis is a technique for delivering ions into a person's skin or tissue by placing a solution, or other medium containing the ions, in contact or close proximity with the skin; the solution or medium containing the ions is typically carried by a first electrode pouch or receptacle. A second or dispersive electrode is placed against the skin within some proximity of the first electrode. Ions are caused to migrate from the ion carrying medium through the skin or tissue by the application of electric current of one polarity to the medium and by application of current of opposite polarity to the second electrode. The current is established by providing a sufficient voltage differential between the first and second electrodes.
The use of iontophoresis to deliver ions into a persons skin or tissue has been discussed in a number of prior art patents including U.S. Pat. Nos. 4,141,359, 4,166,457 and 4,752,285. Examples of electrodes which are useful for making electrical contact with the skin are described in U.S. Pat. Nos 3,862,633; 3,945,384; 3,973,557; 4,250,878; 4,419,092; and 4,477,971. The entire contents of the above-mentioned patents are incorporated herein by reference.
In conventional processes involving delivery of water-based medications into a person's skin by iontophoresis, electrolysis of the water produces hydroxyl (OH.sup.-) and hydrogen (H.sup.+) ions at the negative and positive electrodes, respectively. The reaction at the negative electrode may be represented as follows: 2H.sub.2 O.fwdarw.H.sub.2 .uparw.+2OH.sup.-. The reaction at the positive electrode may be represented as: 2H.sub.2 O.fwdarw.4H.sup.+ +O.sub.2 .uparw.. The hydroxyl and hydrogen ions act as competitors in the iontophoretic process of delivering ionized medications into the skin, resulting in fewer than the desired number of ions being delivered and at a slower rate. In other words, the hydrogen and hydroxyl ions represent unwanted process inhibiting byproducts at least in prior art applications and uses of iontophoresis.
Although iontophoresis is known and used as a mechanism for delivering medicaments into a person's skin or tissue so that the medicaments can operate both locally and systemically, there has been no suggestion, to applicants' knowledge, of using one of the previously unwanted byproducts of iontophoresis to treat skin disorders.
One skin disorder which, in many instances, has persistently resisted effective topical treatment is acne, especially cystic acne. Acne, as well as boils and like disorders, are typically caused by blockage of hair follicles. Such blockage results from a build up of organic material--dead skin cells, sebum secreted into the hair follicle from sebaceous glands located near the root of the follicle, bacteria and dirt. The full chain of events leading ultimately to cystic acne is as follows: (1) plugging of hair follicle giving rise to a "whitehead"; (2) oxidation of the tip of the "whitehead", turning it into a "blackhead"; (3) rupture of the hair follicle walls so that the accumulated contents thereof are discharged into the surrounding tissue to cause inflammation (this inflammation is called a papule or pimple); (4) accumulation of dead white blood cells (pus), bacteria and debris to form a pustule; (5) if pustule is not discharged spontaneously, enlargement (1 cm or more) of the inflamed area--known as a nodule; and (6) liquefaction of the nodule contents to include pus, blood and bacteria--this is cystic acne. Although the natural defense system of the body eventually brings about healing of cystic acne, oftentimes the skin is left with involution and scarring.
If the obstruction or blockage can somehow be cleared and the contents of the hair follicle disgorged at a point in time prior to cyst formation, the site(s) will drain and heal with minimal to no scarring. Even with cystic acne, discharge of the blockage will speed healing and there will be less tissue damage and less scarring.
Approaches to treating acne and like skin disorders have included the use of both topical and systemic medications. For example, desquamating agents, such as tretinoin ("Retin-A") and benzoyl peroxide ("Benzac"), have been used topically to cause peeling of the skin to facilitate disgorgement of follicular obstructions to allow drainage and healing. See Physicians' Desk Reference (PDR), 1989, pp. 1517 and 1518. Typical side effects from use of desquamating agents are inflammation, occasional burning of the skin and photo sensitivity.
Antibiotics, such as clindamycin and tetracycline have also been used topically to eradicate certain bacteria found on the skin, including those found in hair follicles. See pp. 1102 and 2153 of PDR. There are few side effects as a result of the use of topical antibiotics, but these drugs are fairly slow acting and of dubious effectiveness in treating nodular or cystic acne.
Systemic antibiotics (those administered orally), such as tetracycline and erythromycin, or the vitamin A dedrivative isotretinoin ("Acutane") are possibly the most effective medications in treating acne, but the side effects are likewise more serious. See p. 1711 of PDR. Some of these side effects ar detrimental alteration of the normal bacterial contents of the intestines, photosensitivity and temporary liver damage. With systemic isotretinoin, even more serious side effects may occur such as excessive dryness of the skin, eyes and mouth, inflammation of the intestines and fetal malformations.